Control system



Jan. 15, 1946. w R 2,393,025

CONTROL SYSTEM Filed July 1a, 1944 2 Sheets-Sheet I INVENTOR ATTOR EY Jan. 15, 1946.

w. A. DERR bon'rnopsrsmm Filed July 18, 1944 2 Sheets-Sfieet 2 'INVENTOR Wi/lard fl. Der/2 ATTORN Patented Jan. is, 1946 CONTROL SYSTEM Willard A. Derr, Wilkinsburg, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 18, 1944, Serial No. 545,511

7 Claims. I (Cl. 171 -118) My invention relates, generally, to control systems and has reference, in particular, to electrical synchronizing control systems.

Generally stated, it is an object of my invention to provide a synchronizing control system that is simple and inexpensive to manufacture and is easy to operate.

More specifically, it is an object of my invention to provide for synchronizing two or more. alternating-current sources on a common bus when there is no bus potential transformer available.

It is also an object of my invention to provide, in a simple and effective manner, for converting manual switching stations to supervisory control where there is no bus potential transformer available.

Another object of my invention is to provide for selectively connecting a synchronizing device to two or more sources of alternating current which are to be synchronized on a common bus.

Yet another object of my invention is to pro vide for automatically determining whether a common bus to which two or more sources of alternating current may be connected is already energized and, at the same time, provide a synchronizing control potential from one or another of the sources from which it is energized.

Other objects will in part be obvious, and will in part be described hereinafter.

In practicing my invention, synchronizing potential circuits are provided to each of several alternating sources which it may be desired to synchronize on a common bus. Voltage responsive relays associated with each circuit automatically interconnect the circuitsso as to provide" a synchronizing control potential from one or another of the sources which may be connected to the bus. A control switch associated with each source is operated when it is desired to synchronize a particular source with the common bus, to apply to a synchronizing device, a potential from the source and a control potential from one or another of the sources already connected to the common bus, in order to give the operator an indication of when the particular source is synchronized with the bus.

For a more complete understanding of the nature and scopeof my invention, reference may be made to the following detailed description which may be read in connection with the accompanying drawings, in which:

control system embodying the invention in another of its forms.

Referring to Fig. l, the reference numeral I may denote, generally, a control system for synchronizing a plurality of alternating-current sources such as, for example, the generators IOI, I02 and I03 with a common bus I05. As is often the case with relatively small manually-controlled switching stations, potential transformers I06, I01 and I08 may be provided in connection with the generators IOI, I02 and I03, respectively, but the bus I05 may be without a bus potential transformer. Connection of the generators IOI through I03 to the bus I05 may be efiected in any well-known manner, such as by circuit breakers IIO, III, and H2 having operating windings H3. H4 and H5 energizable under the control of suitable switch means represented by the pushbutton switches H1, H8 and H9, respectively.

In order to provide for synchronizing each of the generators with the common bus, synchronizing means such as .the synchroscope I20 may be utilized, having a synchronizing switch I22 associated therewith for effecting connection thereof to potentials from the sources to be synchronized. e

For the purpose of providing the necessary synchronizing potentials, control means such as the relays I24, I25 and I26 may be provided in conjunction with suitable control switches I2'I,

I28 and I29 for energizing the' operating windtential transformers Figure 1 is a diagrammatic view of amanual ings I3I, I32 and I33 thereof. The control means may be operable to connect to the synchroscope I20 a synchronizing potential from the potential transformer of the sourceto be synchronized, and at the same time apply to the synchroscope a synchronizing control potential from a potential transformer of orre of the other sources, de-

pending upon which of the other sources may be connected to the bus. This connection may be effected by providing each of the sources with a selective control relay such as, for example, the voltage-responsive control relays I35, I36 and I3'I, respectively. The control relays I35, I36 and I31 may be provided with operating windings I39, I 40 and MI connected to corresponding phases 0f the sources IOI, I02 and I03 through the po- I06, I01 and I08, re-

spectively,

The selective connection of the synchronizing potential from one or another of the sources connected to the bus may be effected by using normally open and normally closed contact memthe other sources is to be connected to the synchronizing device. Normally open contact members may be provided, in conjunction with each of the circuit breakers, for preventing the application of a synchronizing control voltage to the synchronizing device when the generator associated therewith is operating but is disconnected from the bus by reason of its circuit breaker being open.

With the system in the de-energized position as shown, any one of the circuit breakers may be closed to comiect its associated generator to the bus I which is not energized, since the synchroscope remaining stationary with the source to be synchronized being brought up to frequency indicates that the bus is deenergized. Should the circuit breaker II2 be closed to connect the generator I03 to the bus I05, after the generator has been brought up to speed, the control relay I31 will be already in the energized position, since its operating winding MI is connected directly across the secondary winding of the potential transformer I08. Accordingly, normally open contact members I31a and I310 will be closed, while normally closed contact members I312) and I31d will be open. Since normally open contact members II2a of the circuit breaker II2 are closed, a synchronizing control potential may be made available at the control switches I24 through I26 from the potential transformer I08.

To synchronize the generator I02 with the common bus I05 the switch I25 may be closed to energize the operating winding I32 of the control switch I25, and the synchronizing switch I22 may be operated to the synchronizing position. A synchronizing potential is thereby applied from the generator I02, which is to be synchronized, from the potential transformer I01, through conductors I44 and I45, contact members I250 and I25b, and conductors I41 and I 48, through the synchronizing switch I22 to the synchroscope I20. At the same time, a synchronizing control potential is automatically applied from the generator I03, which is connected to the common bus I05 from the potential transformer I08, through conductor I50, contact members I35b, conductor I5I, contact members I250 and conductor I53, through the synchronizing switch I22 to the synchroscope I20. The other terminal of the potential transformer I08 is connected to the synchroscope through conductor I55, contact members II2a, conductor I55, contact members I35d, conductor I51, contact members I25d, conductor I58 and through the synchronizing switch I22. As soon as the synchroscope I indicates synchronism, the push-button switch II8 may be closed to effect operation of the circuit breaker III to connect the generator I 02 to the bus.

In a like manner, should it be desired to synchronize the generator IIII with the bus I05, the switch I21 may be closed to operate the control switch I24, and the synchronizing switch I22 may be actuated to the operating position. Since both of the control relays I35 and I31 are in the energized position, the synchronizing control potential will be supplied from the potential transformer I08, the same as if only the generator I03 were connected to the common bus. Should the generator I03 be disconnected and only the generator I02 be connected to the bus, the control relay I31 would be in the de-energized position, while the control relay I35 would be in the energized position. Accordingly, the synchronizing control potential would be supplied by the generator I02 from the potential transformer I01, through contact members I35a of the control relay I35. The synchronizing potential from the generator IOI is, of course, supplied by the potential transformer I05 over an obvious circuit through contact members I24a and I24b of the control switch I24. It will thus be seen that a synchronizing control potential is' automatically made available under the control of the control relays for synchronizing any one of the generators with the common bus, whenever one or more of the other generators may be already connected to the bus.

Referring to Fig. 2, the reference numeral I may denote, generally, a synchronizing control system for a plurality of circuit breakers I I0, I II and H2, which may be located at a remote station I I and disposed to be operated from a control station I0 by means of suitable supervisory control equipment over a. single control circuit or channel I2. The supervisory control equipment may be of any suitable character and may, for example, be similar to that shown and described in detail in Patent No. 1,994,908, which issued on March 19, 1935, to Gennero De Croce, and is assigned to the assignee of the present invention. Since the system of the De Croce patent is being used as illustrative of one form of supervisory control equipment with which the present invention may be combined, and the present invention is not concerned with the particular details of all portions thereof, the greater portion of the control station and remote station control and supervisory equipment has been shown boxed. Such of the equipment as has been modified to co-operate with applicants control system has been shown in detail. The same reierence characters have been used to designate elements shown in the original system oi the aforesaid patent and different reference char acters have been used to designate apparatus not 4.0 shown in the patent.

As will be clearly seen from the drawings, the control relays I35, I35 and I31 may be used in exactly the same manner as described hereinbefore in connection with the system of Fig. l, for selectively determining which of the potential transformers I06, I01 or I08 shall provide the synchronizing control potential. In this respect, while the common bus I05 and the connections from the individual sources have been shown as single-phase instead of three-phase as in Fig. 1, It will be understood that this change is merely for the purpose of simplification, so as to reduce the number of conductors and contact members, and in no manner affects the invention. The control switches I24, I25 and I25 are likewise used in an identical manner to select the synchronizing potentials thereby applied to the synchronizing device.

Instead of effecting manual operation of the control switches I24, I25 and I25, as in the system of Fig. 1, operation of the control switches in Fig. 2 may be selectively efiected over the channel I2 by means of control switches 53a, 53b and 530, corresponding to the switch 53 at the control station of the system in the aforesaid patent. Control means, such as the line relays 43a, 43b and 430, corresponding to the line relay 43 of the system of the patent, may be used at the remote station in a similar manner to the line relay 43 of the system of the patent for both connecting the synchronizing equipment I5 to the synchronizing indicating instrument 4') at the control station and eifecting energization of the operating winding of the particular control switch associated with the source it is desired to synchronize with the common bus.

With the system in the de-energized position,

as shown, any one of the circuit breakers IIO,

II I, or II! may be readily closed merely by energizing the respective closing circuit through conductors 82a, 82b or 020 through closing the corresponding one of the control sWitchesGGa, 66b or 660 at the control station, which corresponds to the control switch 60 of the De Croce system, since with the bus de-energi'zed the indicating device 40 would merely give a half-scale reading indicating a de-energized bus. Should the control switch 660 be closed, a predetermined frequency is transmitted over the channel, I2 for effecting operation of the circuit breaker, II2 to the closed position in a manner similar to that described in the De Croce patent. The control relay I31 is thereupon energized, since it is connected directly across the primary winding of the potential transformer I08.

' Should it then be desired to close the circuit breaker I I I, the control switch 531) may be closed to efi'ect operation of the line relay 43b. The synchronizing device I5 is thereby connected to the indicator 40 at the control station, and the operating winding I32 of the control switch I25 is energized over an obvious circuit through contact members of the line relay 431). Accordingly, a synchronizing potential is applied to the primary windings 06 and 24 of the synchronizing transformers from the potential transformer I01 through contact members I25a and I251; of the control switch I25. At the same time, a synchronizing control potential is applied to the primary windings 23 and 35 of the synchronizing transformers through contact members I250 and I20d, normally closed contact members I05!) and 035d and normally closed contact member Ilia. from the potential transformer I08. Accordingly, when the voltages from the potential transformers I01 and I are both in phase and of equal magnitude, the direct current potential applied to the indicating means 40 by the rectifiers I0, I1 and I8 of the synchronizing equipment I5 will be at a minimum indicating synchronism. The circuit breaker control switch 06b at the control station may then be closed to effect closure of the circuit breaker III.

Likewise, when it is desired to close the circuit breaker IIO, the control switch 5301 at the control station may be closed to secure indication of synchronism. The synchronizing potential will be supplied from the potential transformer I06, while the synchronizing control potential, which is representative of the potential on the common bus I05, will be supplied from the potential transformer I08 when both of the circuit breakers I I I and H2 are closed by reason of the circuits provided by the control relays I36 and I31. Should only the circuit breaker III or I I2 be closed, the synchronizing control potential will, of course, be provided from the potential transformer I01 or I00, respectively.

Indication of the operating positions of the circuit breakers may be obtained by means of the indicating circuits established through conductors 86a, 86b and 860 in the manner described in the De Croce patent. Trip circuits for the circuit breakers may be provided also in the same manner described in the De Croce patent over conductors 01a, 01b and 810.

From the above description and the accompanying drawings, it will be apparent that I have provided, in a simple and effective manner, for

synchronizing a plurality of alternating-current sources with a common bus which does not have a bus potential transformer for supplying a synchronizing control potential. The synchronizing control potential is automatically supplied through control circuits provided by the voltage responsive relays and the control switches from one or another of the sources which may be already connected to the common bus. Such a control system makes it possible to apply supervisory control to existing manual switches which do not have a bus potential transformer, and also provides a simple and effective synchronizing system for manual switching stations which are without a bus potential transformer.

Since certain changes may be made in the above-described construction and difierent emnizing voltage to the synchronizing device from a source which is to be synchronized with the bus, and means responsive to the energization of the bus from any of the other sources for applying a synchronizing voltage from one of said sources it? the synchronizing device independently of th us.

2. A synchronizing system for three or more altemating-current sources disposed to be synchronized on a bus without a bus P tential transformer comprising, a synchronizing indicator, switch means associated with each source for applying voltages to the synchronizing indicator from the source to be synchronized and from a source connected to the bus, and means responsive to the voltage of each source operable to selectively determine which of the other sources applies the voltage to the synchronizing indicator.

3. A synchronizing system for a plurality of sources having potential transformers and disposed to be synchronized on a bus not having a potential transformer comprising, a synchronizing device, circuit means including a switch associated with each source operable when the source is to be synchronized to apply control voltages from the potential transformer associated with said source and from one of theother potential transformers to the synchronizing device, and means including control means responsive to the energization of the bus from one or more of said other sources and means responsive to the connection of one of the other sources to the bus for selectively determining which of the other sources shall supply the control voltage.

4. For use in synchronizing any one of three or more altemating-current sources each having a potential transformer on a common bus without means for obtaining a bus a potential, a synchronizing device, means including a switch associated with each source operable to connect the synchronizing device to the potential transformer of a source which is to be synchronized with the bus, and means including relay means responsive to the voltage of each source and to the connection thereof to the bus effective to selectively connect the synchronizing device to the potential transformer of one of the sources connected to the common bus.

5. A synchronizing system for a plurality of alternating-current sources having individual potential transformers and switch means for connecting them to a common bus comprising, a synchronizing indicator, synchronizing switch means associated with each of the sources independently operable to connect the synchronizing indicator to the one source associated therewith, means associated with each source including a relay responsive to the voltage of its associated source for selectively connecting the synchronizing indicator to one of the other sources, and circuit means including means responsive to the position of the switch means for selectively effecting connection of one or the other of the other sources to the synchronizing device when another of the sources is being synchronized.

6. For use in synchronizing at a remote station a plurality of alternating-current circuits on a common bus, at synchronizing indicator located at a control station, a synchronizing device located at the remote station, switch means associated with each one of the circuits for applying a synchronizing potential from said circuit to the synchronizing device for synchronizing said one circuit, means responsive to the energization of the common bus by another of the circuits for selectively applying a synchronizing potential to the synchronizing device from said other circuit independently of the bus, and supervisory control means including a, plurality of control switches at the control station and supervisory control apparatus at the control andremote stations operable to selectively operate the switch means and transmit a synchronism indication from the synchronizing device for operating the synchronizing indicator.

7. A supervisory control system for a plurality of circuit breakers at a remote station each operable to connect an alternating-current circuit to a common bus which is not provided with means for obtaining a synchronizing potential, comprising, a synchronizing transmitter, control means associated with each circuit breaker selectively operable to apply a synchronizing voltage from the associated circuit to the synchronizing transmitter, means associated with each circuit responsive to the energization of the bus from one of the other circuits and co-operative with the control means to selectively connect the synchronizing transmitter to one of the other circuits for obtaining a reference voltage independently of the bus, a synchronizing indicator at a control station, supervisory control apparatus at the remote and control stations for effecting operation of the control means from the control station to cause the synchronizing indicator to operate under the control of the synchronizing transmitter and permit selectively synchronizing the circuits to the bus.

WILLARD A. DERR. 

